[TASK] Avoid invalid methods in FormDefinitionValidationServiceTest

The tests try to configure method mocks that don't
exist. The patch adapts the tests accordingly. They
should receive a bigger overhaul, though.

Resolves: #100416
Related: #100249
Releases: main
Change-Id: Ia1a15a4c9520f2fc4630ea62f50f486ead1131ba
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78387


Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>